I designed a system of lockout buzzers for playing academic trivia games like quizbowl. Commercial versions typically cost upwards of $200, but these can be built for $80-$100 in material costs. If you are interested, reach out to me by emailing annika@worldbrightening.net or finding me on the SoCal Quizbowl Discord server or at a quizbowl event in southern California; I may be willing to build you a buzzer set. Here's a video.